Subway Guitars in Berkeley (aka Fat Dawg Guitars) has a crazy great selection of old-school basses. Lots are one of a kind and rare. It's like a living museum. You can get a sense of the progression of guitar technology and design just by looking around the shop, as many guitars are old enough to be from the early days of electric guitars and basses, before the better designs really popped out.
You won't really find any really high end stuff there, but it's great to see all of the strange, wonderful stringed instruments. There's lots of hollow body basses, old really short scale basses, and other oddities. They'll also have a decent selection of more traditional basses, but don't expect to see any Warwicks, 5-string Ibbys or anything like that. Mostly P-basses, Jazz basses, Rics, etc.
SUBWAY GUITARS: Bargain, Custom, Professional Quality, Retro and Vintage Guitars, Basses & Amps